Improvement in lime and cement kilns



2 Sheets-Sheet 1.

0. BROWN. Lime and Cement Kiln.

'No. 220,337. Patented Oct. 1879.

lio l I i? 4 WTToR N EYS 2 Sheets-Sheet 2.

Lime and Cement Kiln.

No. 220,337. Patented Oct. 7,1879.

I an n n 11 11 um 11' n n I] Man I] n n J 9 J n n n n n n on n nn 11 mum n u u [II] 1:5 13:: I :11

J IZI] ag JV 1| "l5 [:El [3:1 :5

WITNESSES WYN/YIE/OMQR W V'd ATTORN EYS UNITED STATES PATENT OFFICE.

CALVIN BROWN, ,OF MARE ISLAND, CALIFORNIA.

IMPROVEMENT IN LIME AND CEMENT KILNS.

Specification forming'part of Letters Patent No. 220.337, dated October7, 1879; application filed July 12, 1879.

To all whom it may concern: v

Be it known that I, CALVIN BROWN, of Mare Island, in the State ofCalifornia, have invented certain new and useful Improvements in Limeand Cement Kilns; and I do hereby declare thatthe followingis afull,clear, and exact 'and to the letters and figures of reference markedthereon.

Figure 1 of the drawings is a representation of a front of mylime andcement kilns. Fig. 2 is a sectional view through lines 00 or of Fig. 3,Fig. 3 is a plan view, and Figs. 4 and 5 are interior views.

My invention relates to an arrangement of a reverberatoryburning-chamber with a central and perforated furnace and duplicatechimneys for the calcination or burning of lime, cement, plaster, &c.

Heretofore such kilns have been constructed upon necessarily large andexpensive scales, in order to obtain maximum economical results. Theyentail a great and disproportionate amount of labor and expense in theiruse, not only in wear and tear, but in their loading and unloading, inthe consumption of fuel, and the unavoidable mixture of its ashes, slag,850., with the calcined materials. Besides theseinconveniences thereresults the uncertainty of their operation from the impossibility ofalways properly regulating the required heat and of watching itseffects, in consequence of the inaccessible natureof the chambers of thekilns, which forbids the necessary inspection of the calcining processwhile it is'going Two classes of kilns are embraced in the abovestatement, one of which consists of a massive and loftyconstruction,'which, unless some natural and convenient eminence can beavailed of in its location, involves the expense of incline-ways,platforms, 850., or of machine hoisting-works, and the labor for raisingthe materials to be calcined and its fuel to a height varying fromtwenty-five to fifty feet.

The other system is called the annular or ring kiln, which, thoughobviating the objections of high hoisting, involves elaborate andcareful charging, and by its extensive and y the intermittent sort, andhas some advantages in economy over the high kilns; but its arrangementin numerous chambers, alternately subject to heating and cooling, isattended with the deranging effects of this operation; nor does thesystem admit of that uniform and exact burning especiallynecessary inthe prepa ration of hydraulic cement.

Other inconveniences are encountered in all the kilns in common use,which are unnecessary to here state, but which are obviated in theconstruction of my kiln.

My kiln, instead of requiring massive and expensive structures, is ofmoderate dimensions and requires but a small space. It need not be oversix feet high, with chimneys of twenty feet. Instead of necessitatinglarge charges of mixed materials and fuel, whose proper proportions areimpossible to be deter mined except by chance with the ordinary kilns,it needs only small charges of the lime carbonates or raw cement, havinga separate furnace for the fuel, so that itcan be accurately suppliedfor the required purpose and cannot mix with the materials to becalcined, nor deposit its ashes, slag, or cinders with them. In the useof the ordinary kilns, requiring large charges, the whole mass of rawmaterials, consistin g of many tons, mixed with alternate layers offuel, is subjected to a calcination which can only gradually proceed aseach successive layer of fuel is ignited and its heat applied, anoperation that requires several days .before the entire charge can beacted upon,

this process, in the meantime, being attended with an accumulation ofashes from the consumed layers of fuel, with the effect of diminishingthe draft thereby, and consequently the degree of heat is renderedunequal and leaves portions of the material underburned, while in themoretintensel y hot parts of the kiln, where a freer draft happens toact, other portions are liable to be overburned, so that in all suchkilns the burned mass, when cool enough to be withdrawn and handled, hasto be carefully picked over and the properly-calcined pieces separatedfrom the rest.

It sometimes happens that an entire failure results from bad burningwith these kilns, and thus entails a great loss upon the manufacturer,while with small charges, for which my invention is adapted, and in thecase of poor fuel, bad management, or any other cause of an imperfectcalcination, the loss would be limited to the small amount of a singlebatch of materials and the fuel consumed, while the experience of suchan occasion would at once and in the time of a few hours reveal thefault and its remedy.

In my kiln the charges of materials to be calcined are proportioned tothe capacity of the burning-chamber, the applied heat actingsimultaneously upon the whole mass, converting it at once and in a shorttime to the desired condition, the fire in the meanwhile being dulyregulated according to the requirements of the different stages of thecalciuation, whose progress can be readily watched by means of providedarrangements.

My improvement consists in comparatively small kilns in size, determinedby considerations of maximum economies pertaining to the constructionand use of calcining-kilns, and especially in thoroughness of thecalcining process.

In capacity my kilns should not probably exceed that of the quantity ofraw materials required to produce eight average barrels of hydrauliccement, or about one and one-half gross ton.

It also consists in a reverberatory-formed burning-chamber, with aperforated furnace placed through the center thereof, so that the chargeof the materials to be calcined is shielded from direct contact with thefuel, and the heat radiated equally through the chamber and the entiremass.

It further consists in the use of two or more chimneys with fluesleading to them, both directly from the furnace and through openings inthe hearth or sole of the burning-chamber; and it finally consists in ageneral arrangement whereby ease of charging and unloading the materialsto be operated upon is secured, as well as a thorough inspection of thewhole process of calcination and a perfect control of the fire necessarytherefor.

In the accompanying drawings, which fully illustrate my invention, Brepresents the burning-chamber, whose walls and top are constructed offire-bricks, for the reception of the materials to be calcined. C C arechargingholes, by which these materials are introduced to the chamber,and D D are holes for removing samples of the matter undergoingcalcination. All these holes are provided with heattight covers. K K areopenings for unloading the chamber, and are provided with eitherswinging or sliding doors. F is the furnace, placed mostly above thelevel of the hearth, and passing entirely through the burningchamher.This is constructed of fire-bricks, in whole or in sections, of suitablematerials, provided with openings 0 for the passage of heat, &c., andprovided with doors and grates. E E are the upper or direct flues to thechimneys, separated and spaced so as to favor the diffusion of heat. G Gare openings through the hearth, communicating downward with thepassages H H to the lower flues, I I. J J are the chimneys, providedwith diaphragms L L, to secure uninterrupted draft by preventing theimpingement of heat-currents, 850., entering from opposite directions.The chimneys are also provided with dampers placed on their tops orotherwise. M is the ash-pit, extending entirely under the furnace andprovided with a door at each end.

The operation of the kiln is as follows: The materials to be calcined,supposing it to be for artificial hydraulic or Portland cement, areintroduced into the chamber B through its chargin g-holes C O, and also,if desired, through the openings K, an d properly distributed, by meansof iron rakes or otherwise, over the hearth and over the top of thefurnace F. All the openings of the chamber are then closed, and thefurnace, charged with fuel, is fired. By the peculiar arrangement of thefurnace-openin gs O the direct or upper flues, E, the hearthopenings G,communicating with the lower flues, I, and the reverberatory action ofthe soffit of the burning-chamber, the heat is radiated and thoroughlydifl'used through the entire mass subjected to its efl'ects. By theespecial disposition of the furnace-openings 0, as shown, the heat issupplied according to the greater or lesser amount required at variouspoints of the mass to be calcined. The tendency of heat being to rise,and thus to concentrate in the higher part of the furnace, over whichthe calcining material would be in less quantity, the openings are theremade fewer, while upon its sides and near the hearth, where the greatbulk of the mass is placed, they are more numerous and of a greatertotal capacity or outlet, and thus admit of a larger quantity of heat toact upon the greater bulk of the interior of the charge.

The fire in the furnace F is maintained until the process is completed,and, if necessary, additional fuel may be introduced directly into theburning-chamber B through the holes D D upon such portions of the chargeas may appear to require it.

In the calcining process as involved in the conversion of artificial oreven natural hydrauliccement materials, the management of the fire isessential, and can be determined only by the indications of thedifferent stages of this process, as shown by the inspection of samplesof the charge taken from time to time from the burning-chamber, asprovided for by the holes D. It is regulated by the fuel-supply aud theoperation of the chimney-dampers and that of the ash-pit and furnacedoors, through which the oxygen 'for combustion is supplied.

Upon the completion of the calcination of the charge it is withdrawn,while still hot, through the openings K, and a fresh one of rawmaterials supplied to the chamber, thus making it available forperpetual operation, and, by constantly maintaining its heat, preventingits waste and the damaging effects of alternately heating and coolingthe masonry and works of the kiln.

I have constructed kilns upon the general principle above described,with the central furnace placed entirely below the level of the hearth,the heat in such cases passing through openings in the hearth itself;but the method of placing it nearly upon and partly above this level,'asherein specified and shown by the drawings, brings the fire nearer toand in .closer action with the charge in the chamber,

and thus reduces the amount of fuel and performs the work of calcinationin less time.

CALVIN BROWN.

Witnesses WM. E. Cox, J r., E. A. WILLATS.

